﻿Shader "Custom/MoveUV"
{
	Properties
	{
		_MainTex ("Texture", 2D) = "white" {}
		_Speed("Rotate Speed",Range(0,4))=1
		_ClipGray("Gray Factor",Range(-1,1))=0.2
		_MidYValue("_MidYValue",float)=1
		_CloudHeight("_CloudHeight",float)=5
		_TaperPower("_TaperPower",float)=3
		
	}
	SubShader
	{
		Tags { "RenderType"="Opaque" }
		//Tags { "RenderType"="Transparent" }
		LOD 100

		Pass
		{
		    //Blend SrcAlpha OneMinusSrcAlpha
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag			
			#include "UnityCG.cginc"

			sampler2D _MainTex;
			float _Speed;
            float _ClipGray;
            float _MidYValue;
            float _CloudHeight;
            float _TaperPower;
			struct a2v{
				float4 vertex:POSITION;
				float4 texcoord:TEXCOORD;
			};
			struct v2f{
				float4 pos:POSITION;
				float4 uv:texcoord;
				float4 posWorld:TEXCOORD1;
			};

			v2f vert(a2v v){
				v2f o;
				o.pos=UnityObjectToClipPos(v.vertex);
				o.uv=v.texcoord;
				o.posWorld = mul(unity_ObjectToWorld,v.vertex);
				return o;
			}

			fixed4 frag(v2f i):SV_Target{
				//扭曲效果
//				fixed2 uv = i.uv - fixed2(0.5,0.5);
//				float angle = _Speed * 0.1745/(length(uv) + 0.1);//加0.1是放置length（uv）为0
//				float angle2 = angle * _Time.y;
//				uv = float2(uv.x*cos(angle2)-uv.y*sin(angle2),uv.y*cos(angle2)+uv.x*sin(angle2));
//				uv+=fixed2(0.5,0.5);
//				fixed4 c = tex2D(_MainTex,uv);
//				return c;

				//缩放
				//float4 uv = i.uv;
				//uv.x*=_Speed;
				//uv.w=0.5;
				//return tex2D(_MainTex,uv);

				//旋转
//				float2 uv=i.uv.xy-float2(0.5,0.5);
//				uv=float2(uv.x*cos(_Speed*_Time.y)-uv.y*sin(_Speed*_Time.y),uv.y*cos(_Speed*_Time.y) + uv.x*sin(_Speed*_Time.y));
//				uv+=float2(0.5,0.5);
//				fixed4 lateUV = tex2D(_MainTex,uv);
//				return lateUV;

				//平移
				//return tex2D(_MainTex,i.uv - _Time.x*fixed2(2,0)* _Speed);
				
				fixed xV = _Speed * _Time.x;
				fixed yV = _Speed * _Time.x;
				
				fixed4 colH = tex2D(_MainTex, i.uv + float4(xV,0,0, 0));//动太快，这里相当于xV * Vector.One(实测只需要0.02）
				fixed4 colV = tex2D(_MainTex,i.uv + float4(0,yV,0,0));
			    
			    float vFallOff = pow(saturate(abs(_MidYValue - i.posWorld.y)/(_CloudHeight*0.25)),_TaperPower);
				fixed4 col = colH * colV;
				clip(col.r  -_ClipGray);
		
				return col;

			}

			ENDCG
		}
	}
}

